(1) Field of the Invention:
This invention relates to an electrostatic particle spraying apparatus, in particular, an apparatus where a conventional aerosol spray can is employed to dispense a spray of particles that are charged with a predetermined polarity by an electrode of the apparatus positioned in the projected path of particle spray from the aerosol can.
(2) Description of the Related Art:
Electrostatic particle spraying systems of the type provided by the present invention commonly comprise an electrostatic spray gun or a manually held particle spray directing device that employs a nozzle supplied with a pressurized fluid to be sprayed on a substrate surface. An operator selectively dispenses a fine spray of fluid particles from the spraying device in a projected path toward the substrate. Fluids commonly dispensed by such devices include paint and pesticides. An electrode selectively connected to a source of D.C. voltage is mounted to the device in a position proximate to the projected path of particle spray. The electrode is selectively connected to the source of D.C. voltage by a manually operated switch to produce a high D.C. potential in the electrode.
The high electric potential of the electrode induces an electric charge in the fluid particles that are sprayed from the nozzle of the device. The induced charge of the particles sprayed from the nozzle is of a predetermined polarity, and the like charge of the particles facilitates in the atomization of the fluid sprayed from the nozzle of the device. As is known in the art, the electrostatic charging of the fluid particles sprayed from the nozzle of the device enhances the depositing of the particles on a grounded substrate being sprayed.
The spray guns or spraying devices of conventional electrostatic particle spraying apparatus commonly use a source of D.C. voltage and a source of fluid to be sprayed that are both separate from the spray gun. These systems typically employ a power converter or booster that transforms the commercially available low A.C. voltage power to a high D.C. voltage to be supplied to the electrode of the gun. Spray guns of this type are commonly connected to separate voltage boosters or multipliers by bulky high voltage cables that extend between the voltage booster and the gun. Some conventional spray guns contain voltage boosters within the structure of the guns. These types of spray guns are commonly connected by low voltage wiring to a low voltage D.C. source that, in turn, is connected to a source of commercially available A.C. voltage power. The A.C. voltage is converted to a low D.C. voltage by the low voltage D.C. source, and the low D.C. voltage is supplied to the voltage multiplier contained in the gun where it is converted to the high D.C. voltage required to charge the electrode of the gun.
The source of fluid to be sprayed from the gun is also typically separate from the gun itself and is connected to the gun by a bulky supply hose. Electrostatic particle spraying apparatus of the type described above are disclosed in the U.S. Pat. Nos. 3,731,145; 4,258,655; and 4,613,075.
Conventional electrostatic particle spraying apparatus of the type described above are disadvantaged in that their connections to separate power and paint sources by bulky electric cables and fluid hoses render the spray guns awkward to manipulate during a particle spraying operation. Several types of electrostatic spraying apparatus have been developed in efforts to overcome the disadvantages of the above described electrostatic systems. These include electrostatic spraying apparatus having self contained voltage sources and self contained supplies of fluid to be sprayed. However, these self contained electrostatic spraying apparatus require specialized cannisters for their fluid supplies and are not readily adaptable to use with conventional aerosol spray cans of paint or pesticides.
The present invention overcomes the shortcomings of the prior art electrostatic particle spraying apparatus by providing a self contained hand-held electrostatic particle spraying device that is adapted to use a conventional aerosol spray can as its source of fluid particles to be electrostatically charged and has no bulky hose connection to an external fluid source. The spraying device of the present invention also comprises a self contained high D.C. voltage source and has no bulky electric cable connections to an external voltage source. The self contained source of high D.C. voltage is selectively connected to an electrode protruding into the projected path of particle spray from an aerosol spray can inserted into the device.
It is therefore an object of the present invention to provide an improved self contained electrostatic particle spraying apparatus that contains its own source of high D.C. voltage and its own source of fluid particles to be sprayed in the form of a conventional aerosol spray can. The apparatus is manually operated to spray fluid particles from the aerosol can in a projected path toward a grounded substrate while simultaneously inducing an electric charge of a predetermined polarity in the particles of fluid sprayed from the aerosol can to enhance the depositing of the charged particles on the substrate.